Carbodiimide catalysts and processes

ABSTRACT

Phosphine oxides are prepared from terpenes and are found to be valuable as catalysts in the condensation of isocyanates to yield carbodiimides.

United States Patent [191,

Hansen 1 Jan. 28, 1975 I 1 CARBODIIMIDE CATALYSTS AND PROCESSES [75] Inventor: Robert L. Hansen, Roseville, Minn.

[73] Assignee: Minnesota Mining and Manufacturing Company, Saint Paul, Minn.

[22] Filed: June 8, 1973 [21] Appl. N0.: 368,355

[52] U.S. 260/606.5 P, 260/453 A, I 260/453 AL, 260/453 AR, 260/453 P, T 260/471 C, 260/551 [51] Int. Cl. C07f 9/28 [58] Field of Search 260/6065 P [56] References Cited UNITED STATES PATENTS 2,663,737 12/1953 McCormack ..260/606.5P

OTHER PUBLICATIONS Turner et 211., Condensed Chemical Dictionary, Reinhold Pub. Corp. N.Y., 1950, 4th ed.

Primary ExaminerArthur P. Demers Attorney, Agent, or FirmAlexander, Sell, Steldt & DeLaHunt [57] ABSTRACT Phosphine oxides are prepared from terpenes and are found to be valuable as catalysts in the condensation of isocyanates to yield carbodiimides.

6 Claims, N0 Drawings where n is an integer from to a large number, preferably not over about 20. R and R' may be the same or different, substituted or unsubstituted monovalent organic radicals free from isocyanate reactive hydrogen atoms and R" is a polyvalent, generally divalent, organic radical free from isocyanate reactive hydrogen atoms. Although R" may be, for example, trivalent to provide a branch which may be free of or may contain carbodiimide groups, a divalent group is preferred when soluble or thermoplastic materials are desired. When R" is polyvalent, branched or crosslinked polycarbodiimides result. Different R" groups may be used together to give slight branching in order to modify properties. Any or all of the groups R, R" or R' may contain fluoroaliphatic radicals to provide oil and water repellent characteristics and to minimize solubility in common solvents. The carbodiimides have many known uses, such as molding powders, coatings, films, and treating compositions for a variety of substrates. In general, carbodiimides are prepared by the reaction of mono-, dior poly-isocyanates in the presence of suitable catalysts so that the isocyanate groups condense with the liberation of carbon dioxide to form the carbodiimide linkages. In general, it is preferred that carbodiimides include at least lpercent and preferably IOpercent or more of N=C=N groups. Because of the wide variety of reactions that isocyanate groups can undergo, selection ofa suitable catalyst is an important factor in preparing carbodiimides.

One class of suitable catalysts is the phosphacyclopentyl derivatives, as prepared in U.S. Pat. Nos. 2,663,737, 2,663,738, and 2,663,739. The use of these materials as catalysts for carbodiimide formation is described in U.S. pat. No. 2,853,518 and especially in U.S. Pat. No. 2,853,473. These materials are, in many cases quite effective as catalysts for the desired condensation reaction, but their preparation requires extended times and yields are frequently low. This class of phosphorus compounds are included in the terms phospholine, phospholine oxide, phospholine sulfide, phospholidines and the oxides and sulfides thereof.

Another class of phosphorus-containing compounds which has been described as useful as catalysts for the carbodiimide reaction are phosphetane oxides, in which the quinquevalent phophorus bearing an alkyl, aryl or alkyl group and an oxide oxygen is a member of a four-membered ring, the other three being methylene or alkyl substituted methylene groups, as described in British Pat. No. 1,215,157. The Phosphetane oxides are generally prepared by condensation of a substituted dichlorophosphine with a noncyclic aliphatic olefin hearing a tertiary carbon atom beta to the olefinic carbon atom in the presence of a Friedel-Crafts catalyst such as aluminum chloride, followed by hydrolysis. Such a structure in skeletal form is The method of preparation is convenient, but the required noncyclic olefins are relatively expensive or inaccessible.

It is an object of this invention to provide a novel catalyst for the condensation of isocyanates and for polyisocyanates to carbodiimides and particularly compounds containing the carbodiimide linkage. Another object of the invention is to provide a new process for the production of polycarbodiimides. A further object of the invention is to provide a process for the production of phosphine oxides and particularly a process which is adapted to the use of readily available materials. Other objects will become evident hereinafter.

In accordance with these and other objects of the invention, a new class of phosphine oxides has now been discovered which can be prepared conveniently from inexpensive, readily available raw materials and which provides effective catalysis for thecondensation of mono or polyisocyanates to carbodiimides. In these compounds the phosphorus atom is believed to be a member of a ring consisting additionally of three carbon atoms, Le, a phosphetane oxide, but at least part of the annular carbon atoms are themselves part of a polynuclear alicyclic structure. A preferred class of these materials is those having the formula C H PRO, wherein R is alkyl, aryl or aralkyl, of up to about 10 carbon atoms, substituted on the phosphorus atom. Particularly preferred is phenyl. They are conveniently prepared by reaction in the presence ofa Friedel-Crafts catalyst of a substituted dihalophosphine, e.g., RPCl particularly phenyl dichlorophosphine, and a bicyclic terpene of the class of camphene, alpha and beta pinene, and sabinene. The preferred starting material is camphene.

Suitable dihalophosphines include particularly dichlorophosphines having alkyl or aryl group attached directly to phosphorus. In particular, alkyl group of l to about 10 carbon atoms and aryl groups such as phenyl, tolyl, xylyl and the like of about 6 to 10 carbon atoms and preferably phenyl. The alkyl or aryl groups may be substituted by compatible groups which are unreactive with aluminum chloride or isocyanate groups under reaction conditions and are free from non aromatic unsaturation. Preferably, the alkyl and aryl groups are unsubstituted.

The reaction is suitably carried out by forming a complex between a Friedel-Crafts catalyst such as anhydrous aluminum chloride or ferric chloride and the substituted dihalophosphine, conveniently in the presence of inert solvents such as methylene chloride, or nitrobenzene. This complex is then reacted with the bicyclic C H terpene at a temperature between 25 and C., conveniently at a temperature of about 1530C. The product may be used as a catalyst in the solvent as formed, as recovered by evaporation of the solvent, or ina more purified form, for example, that derived by vacuum fractionation of the reaction mixture.

I TCO =N Catalygt Q N C invention Representative organic monoisocyanates which may be used include methylisocyanate, ethylisocyanate, butylisocyanate, octylisocyanate, octadecylisocyanate, allylisocyanate, vinylisocyanate. pentylisocyanate, phenylisocyanate, o-tolueneisocyanate, P- tolueneisocyanate, O-nitrophenylisocyanate, pchlorophenylisocyanate, p-methoxyphenylisocyanate, p-biphenylylisocyanate, cyclohexylisocyanate, and decahydronaphthyl-isocyanate. It is to be understood that mixtures ofthese monoisocyanates may be used to form unsummetrical or mixed carbodiimides.

The process of the present invention may also be carried out by using a polyisocyanate, such as a dior triisocyanate. When using an organic diisocyanate, according to the process of the present invention, a condensation polymer having repeating carbodiimide linkages is prepared which may be of a high molecular weight and is substantially linear. The use of an organic diisocyanate alone may be illustrated as follows:

=N-)-,,R"NCO+nCO 2 wherein R" is a bivalent organic radical and n is l or more. Organic diisocyanates which may be used in the process of the present invention include 2,4-tolylene diisocyanate, m-phenylene diisocyanate, 4-chloro-l,3- phenylene diisocyanate, 4,4'diisocyanate, 1,5- naphthylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 4,4- methylenedicyclohexylene diisocyanate, and 1,5- tetrahydronaphthylene diisocyanate. Mixtures of two or more of these organic diisocyanates may be used in which case the bivalent organic radical R" in the above formula will not be the same in each recurring unit. It is further contemplated to employ mixtures of monoisocyanates and polyisocyanates, preferably in proportions or in sequential operations such that the monoisocyanates will provide caps or terminal groups. It is also to be understood that isocyanate-terminated polymers may be used in the process of the present invention so as to prepare substantially linear polymers groups with a molar excess of an organic diisocyanate so as to provide an isocyanate-terminated polymers. Here again it is to be understood that mixtures of two or more different isocyanate-terminated polymers may be used in the process of the present invention. in which case the bivalent organic radical R" in the above formula will not be the same in each recurring unit. It is readily apparent that any of a wide variety of isocyanate-terminated polymers may be used in the process of the present invention.

Although aliphatic isocyanates provide useful carbodiimides, e.g., hexamethylene diisocyanate. aromatic isocyanates and diisocyanates such as tolylene diisocyanate are preferred because they react more rapidly to form carbodiimides. When substantial quantities of a tri(or higher) isocyanate are present in the reaction mixture, the resulting polycarbodiimide tends to be cross-linked, therefore infusible and insoluble. When small amounts of tri(or higher) isocyanate are present. a branched polycarbodiimide can be prepared which is soluble and fusible, generally having the same characteristics as the linear carbodiimides produced from mono and diisocyanates. Representative compounds containing more than two free isocyanate groups which may be used in amounts up to one molecule per molecule of product carbodiimide include 3.4.6- triisocyanatotoluene, p-isocyanatophenyl 2.4- diisocyanathophenyl ether, and compounds which are prepared from trifunctional reactants, such as the reaction product of 1 mol of castor oil with 3 mols of a diisocyanate, so as to obtain a compound having three free isocyanate groups. It is readily apparent that any of a wide variety of organic compounds containing more than two free isocyanate groups may be used in the process of the present invention.

A particularly useful substituent on the isocyanate component is a fluoroaliphatic radical. The fluoroaliphatic radical is preferably a fluorinated, saturated monvalent nonaromatic radical of at least three carbon atoms and generally less than about 20 carbon atoms. The aliphatic chain may be straight, branched, or if sufficiently large, cyclic, and may include catenary oxygen or trivalent nitrogen atoms bonded only to carbon atoms. Such hetero atoms are essentially inert. A fully fluorinated radical is preferred, but hydrogen or chlorine atoms may be present for two carbon atoms and preferably the radical contains at least one terminal perfluoromethyl group. Completely fluorinated aliphatic radicals containing about 5l2 carbon atoms are most preferred. The fluoroaliphatic radical may be appended to a diisocyanate such as containing a plurality of intralinear carbodiimide linkages. Representative isocyanate-terminated polymers which may be used include the reaction products of a polymer having terminal hydroxyl, amino, or carboxyl r a rr or part of a monoisocyanate such as C F, SO N(C H )C H O CNHC H (CH )NCO in which case the fluoroaliphatic radical forms a part of the terminal group of the product carbodiimide. Such lluoroaliphatic radical substituted carbodiimides suitably contain from about 5 to 45 percent by weight of carbon-bonded fluorine in the form of fluoroaliphatic radicals and are useful for the preparation of surface finishes to confer oil and water repellency and stain resistance, for example, to fabrics, especially fabrics consisting of synthetic fibers.

The invention is now more particularly illustrated by examples showing the production of a camphene phosphine oxide and the use thereof in preparing a carbodiimide.

EXAMPLE I To a one liter round bottom flask fitted with stirrer, thermometer and funnel is added a slurry of 66.5 grams of aluminum chloride in 350 grams of CH Cl and to this is added 89.5 grams of phenyl dichlorophosphine. Other alkyl and aryl dichlorophosphines are employed similarly. The flask is placed in a cooling bath to maintain the temperature of the contents at 25C. A solution of 68 grams of camphene in 150 grams of methylene chloride is added to it slowly with stirring. Stirring is continued for 1 hour after addition is completed, and the solution is then carefully poured, with stirring, into 750 ml. of an ice-water slurry. The lower methylene chloride layer is drawn off, washed first with an equal volume of Spercent aqueous sodium bicarbonate, then with a saturated sodium chloride solution, and is finally dried over molecular sieve. Removal of solvent under reduced pressure at 35C. leaves a residual viscous oil which is further purified by distillation at 0.5 torr and l80l90 C. to give a colorless, viscous syrupy material. The product is shown by vapor phase chromatography to contain about 97 percent of a single component, C H POC H designated camphene phenylphosphine oxide. The molecular weight by mass spectroscopy agrees with the empirical formula. The solution, the residual oil and the distillate are each effective catalysts for the formation of carbodiimides from isocyanates. The structure of the camphene phenyl phosphine oxide is not certain because of the possibility of rearrangements in the terpene structure as well as the probability of geometrical isomers.

EXAMPLE Il ln a three liter glass flask equipped for distillation cooling and stirring is placed 77.2 grams of C F, SO N(C H )C H OH dissolved in 174.0 grams of methyl isobutyl ketone. The solution is dried by distillation of 50 grams of the ketone and then is cooled to 90C. and 72.7 grams of 2,4-tolylcne diisocyanate is added. The vapor space is filled with nitrogen gas to a slight positive pressure and the reaction mixture is heated at 125C. with stirring for 1 hour. The flask and contents are cooled to about 30C. and 6.0 grams of the 25 percent solution of camphene phenyl phosphine oxide in methylene chloride, prepared in Example I is added. The flask is heated to C. and maintained there, with stirring for 3 hours, or until infra-red analy sis confirms a substantially complete conversion of isocyanate to carbodiimide. The product can be used directly to solvent-treat fabrics to provide an oil and water repellent, stain resistant treatment, or the material may be converted, e.g., to an aqueous emulsion, with or without additional polymeric material, for the treating solution.

EXAMPLE III The procedure of Example I is repeated using beta pinene and a solution of beta pinene phenyl phosphine oxide in methylene chloride is obtained. The material is rather high boiling. A portion of the solution is employed at 25 percent concentration as was the phosphine oxide in Example ll to catalyze formation ofcarbodiimide. Similar results are obtained and the resultant carbodiimide is employed in the treatment of fabrics with satisfactory results.

EXAMPLE IV When other alkyl and aryl dihalophosphines are used in the procedures of Example I and Ill, other terpene alkyl and aryl phosphine oxides are obtained which are also useful as catalyst for the production of carbodiimides using the procedure of Example II or with other monoor polyisocyanates.

What is claimed is:

1. A bicyclic terpene alkyl or hydrocarbyl aryl phosphine oxide wherein alkyl is of l to 10 carbon atoms and hydrocarbyl aryl is of 6 to 10 carbon atoms.

2. Camphene phenyl phosphine oxide.

3. Pinene phenyl phosphine oxide.

4. A process for the production of alkyl or hydrocarbyl aryl phosphine oxide comprising condensing a bicyclic C l-l terpene with l to 10 carbon atom alkyl phosphine dihalide or 6 to 10 carbon atom hydrocarbyl aryl phosphine dihalide in the presence of Friedel- Crafts catalyst.

5. The process according to claim 4 wherein the terpene is camphene.

6. The process according to claim 4 wherein the phosphine dihalide is phenyl dichlorophosphine.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORECTION PATENT NO. 3,862,989

DATED January 28 1975 INVENTOR(S) Robert L. Hansen It is certified that rror appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 65, "line." should read as in a Column 3, line 42, "MJt'diisocyanate," should read as t, t-'-biphenylene diisocyanate,

Signs and gealed this thirtieth D ay 0f September 1 9 75 [SEAL] v A ttest:

RUTH C. MASON C nmmixsinncr oj'lale'ms and Trademarks 

1. A BICYCLE TERPENE ALKYL OR HYDROCARBYL ARYL PHOSPHINE OXIDE WHEREIN ALKYL IS OF 1 TO 10 CARBON ATOMS AND HYDROCARBYL ARYL IS OF 6 TO 10 CARBON ATOMS.
 2. Camphene phenyl phosphine oxide.
 3. Pinene phenyl phosphine oxide.
 4. A process for the production of alkyl or hydrocarbyl aryl phosphine oxide comprising condensing a bicyclic C10H16 terpene with 1 to 10 carbon atom alkyl phosphine dihalide or 6 to 10 carbon atom hydrocarbyl aryl phosphine dihalide in the presence of Friedel-Crafts catalyst.
 5. The process according to claim 4 wherein the terpene is camphene.
 6. The process according to claim 4 wherein the phosphine dihalide is phenyl dichlorophosphine. 